|Funding Agency||National Science Foundation|
Crystalline and amorphous structures stand in two extremes in term of atomic configuration in solids. In a crystalline structure, atoms are arranged according to predefined rules while in amorphous structures atoms are packed in random fashion. Quasicrystalline structure can be considered as a state between the two. Materials of crystalline and amorphous structures, represented by gold and window glass, respectively, have been known to mankind for thousands of years. In contrast, materials of quasicrystalline structure were recently discovered in 1980's, and many aspects remain to be studied. An aluminum-copper-iron alloy of Al65Cu20Fe15 composition is one of the most studied alloys related to quasicrystalline phase. This alloy, when it is prepared by arc melting, is porous, consisting of multiple voids with particles of different morphologies on the surface. Despite previous extensive studies, there are many different opinions about the make-up and formation processes of these particles, probably because no previous studies have placed focus on them. Further, a primary study of these particles by the present principal investigator has revealed new details that deserve further investigation. This project will carry out a detailed study on these particles. In addition to scientific contribution, the project has significant impact on the education at Clarion University, a rural teaching college. First, it enables the principal investigator to stay active in research field and to integrate latest developments into teaching. Second, it gives students a rare opportunity to experience or observe authentic scientific research, strengthening their confidence in pursuing careers in science and technology. Annually, the project will reach students in the following ways: eight undergraduate students will work on the project either as paid research assistants or as volunteers; two local high school students will be given opportunity to work on the project for a week in summer; approximately 100 undergraduate students will be exposed to the project through introduction in course teaching; and interested students from one neighboring high school will be invited to campus to learn about the project from principal investigator and undergraduate students.
Six important problems related to the morphology and crystal orientation of particles on the surface of the voids of as-prepared Al65Cu20Fe15 alloy have been identified, which have either not been reported previously or have not been well understood. For example, there is strong evidence indicating that one type of particle consists of multiple phases, in contrast to previous single phase assumption. There are experimental results that lead to a speculation about the orientation relationship between quasicrystalline thin film and crystalline substrate, which needs to be confirmed and investigated further. These problems will be clarified experimentally by using a Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS) and Electron Backscattering Diffraction (EBSD), to be carried out at the principal investigator's home institute. The studies will be supplemented by theoretical analysis and Transmission Electron Microscope (TEM) examinations to be performed in collaboration with other institutes. Because of the clear and unique focus, this project will generate sufficient data to fill in the missing details and to clarify conflicting reports about the microstructure of this well-known alloy, thus establishing a reliable and consistent model about the phase formation process.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.